1. Field of the Invention
The present invention relates to an automatic stop/restart device for an internal combustion engine, which automatically stops the internal combustion engine when a predetermined automatic stop requirement is satisfied while the internal combustion engine is in operation and restarts the internal combustion engine when a predetermined restart requirement is satisfied while the internal combustion engine is in an automatically stopped state.
2. Description of the Related Art
In recent years, some internal combustion engines to be mounted in a vehicle use an automatic stop/restart device (so-called idling-stop device) for the internal combustion engine mainly for the purpose of reduction in fuel consumption. The automatic start/restart device for the internal combustion engine automatically stops the internal combustion engine when a predetermined automatic stop requirement is satisfied according to a deceleration operation and a vehicle stop operation, which are performed by a driver who is driving the vehicle. The automatic start/restart device for the internal combustion engine automatically restarts the internal combustion engine when a predetermined restart requirement is satisfied according to an operation for starting the vehicle, which is performed by the driver.
The restart performed by the automatic stop/restart device for the internal combustion engine has the following problem. When the driver performs the operation for starting the vehicle (restart request operation) while the internal combustion engine is rotating by inertia after being automatically stopped, a pinion gear, which is provided to a starter for performing an operation for starting the internal combustion engine, and a ring gear, which is connected to a crankshaft of the internal combustion engine, cannot be brought into meshing engagement with each other because of a difference in rotation speed between the ring gear and the pinion gear. Therefore, it is necessary to wait to restart the internal combustion engine until the internal combustion engine is stopped, and hence there is a problem in that the internal combustion engine is not restarted in response to the restart request operation by the driver.
In order to solve the problem described above, the following technology is disclosed. According to the technology, while the rotation speed of the ring gear and the rotation speed of the pinion gear are monitored in response to the restart request operation, the pinion gear is moved to be brought into meshing engagement with the ring gear after the rotation speed of the pinion gear comes into synchronization with the rotation speed of the ring gear. In this manner, the restart is performed (see Japanese Patent Application Laid-open No. 2005-330813).
However, the technology described in Japanese Patent Application Laid-Open No. 2005-330813 has the following problems. Specifically, a sensor for detecting the rotation speed of the ring gear and the rotation speed of the pinion gear is required. Further, control means for the pinion gear (starter motor) becomes complicated because the rotation speed of the pinion gear is adjusted so that the rotation speed of the pinion gear and the rotation speed of the ring gear come into synchronization with each other while the rotation speeds of the ring gear and the pinion gear are being monitored. In addition, the use of a shunt coil for the starter motor for adjusting the rotation speed of the pinion gear complicates a device structure of the starter to disadvantageously increase the weight and cost of the starter.